Group iii nitride semiconductor light-emitting device and production method therefor

ABSTRACT

The Group III nitride semiconductor light-emitting device has an insulating multilayer film intervening between a second semiconductor layer and a transparent electrode. The insulating multilayer film serves as a distributed Bragg reflector and is formed in a region including a projection area obtained by projecting a p-electrode to the p-type contact layer. The insulating multilayer film has a first region and a second region, wherein the first region has a layer thickness greater than 95% of the maximum film thickness of the insulating multilayer film, and the second region has a layer thickness not greater than 95% of the maximum film thickness of the insulating multilayer film. The second surface of the insulating multilayer film in the second region has a slope having a dent portion denting toward the first surface of the insulating film.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present techniques relate to a Group III nitride semiconductorlight-emitting device and to a method for producing the device. Moreparticularly, the techniques relate to a Group III nitride semiconductorlight-emitting device having a current-blocking layer and to a methodfor producing the device.

2. Background Art

In a Group III nitride semiconductor light-emitting device, currenttends to flow a region directly under the p-electrode, while currentflow is impeded in a region away from the p-electrode. Due to thelocalization of current flow, the overall emission efficiency of thelight-emitting device may be suppressed.

In one solution for preventing such localization of current flow, acurrent-blocking layer is placed directly under the p-electrode. Forexample, Patent Document 1 discloses a technique in which a transparentinsulating film is formed as a current-blocking layer (see, for example,paragraphs [0017] and [0018], and FIG. 1 of Patent Document 1). Byvirtue of the current-blocking layer, light emission can be caused tooccur selectively in a light-emitting layer (see, for example, paragraph[0004] of Patent Document 1).

Patent Document 2 discloses a light-emitting device of a laser lift-offtype. In the light-emitting device, a current-blocking layer is disposedbetween the p-type GaN layer and the p-electrode. The current-blockinglayer serves as a distributed Bragg reflector (DBR). Thecurrent-blocking layer diffuses current, and the distributed Braggreflector (DBR) reflects light emitted from the light-emitting layertoward the light extraction face on the n-type semiconductor layer side(see, for example, paragraphs [0010] and [0028] of Patent Document 2).

Patent Document 1: Japanese Patent Application Laid-Open (kokai) No.2008-192710

Patent Document 2: Japanese Patent Application Laid-Open (kokai) No.2007-150310

Meanwhile, in some cases, a face-up-type light-emitting device, having alight-extraction face on the p-type semiconductor layer side, may beprovided with a current-blocking layer also serving as a distributedBragg reflector (DBR). In such case, the light emitted from thelight-emitting layer toward the p-electrode is reflected by thedistributed Bragg reflector (DBR), whereby the light is not absorbed bythe p-electrode and is reflected toward the semiconductor layer.Although the light is not absorbed by the p-electrode, the light may bere-absorbed by the light-emitting layer. In order to suppress there-absorption of light, the current-blocking layer also serving as adistributed Bragg reflector (DBR) preferably has a somewhat small size.

From another viewpoint, semiconductor light-emitting devices preferablyattain sufficient current diffusion over a desired device region. Forthis purpose, the current-blocking layer preferably has a somewhat largesize. However, when a wide-area current-blocking layer is formed so asto attain sufficient current diffusion, the light to be extracted to theoutside is undesirably reflected toward the semiconductor layer.

SUMMARY OF THE INVENTION

The present techniques have been conceived in order to solve theaforementioned technical problems involved in the conventionaltechniques. Thus, an object of the present techniques are to provide aGroup III nitride semiconductor light-emitting device which realizessufficient current diffusion in the light emission face of thelight-emitting layer and which attains suitable light extraction to theoutside. Another object is to provide a method for producing thelight-emitting device.

In a first aspect of the present technique, there is provided a GroupIII nitride semiconductor light-emitting device comprising:

a first semiconductor layer having a first conduction type;

a light-emitting layer disposed on the first semiconductor layer;

a second semiconductor layer having a second conduction type, the layerbeing disposed on the light-emitting layer;

a transparent electrode disposed on the second semiconductor layer;

a first electrode electrically connected to the first semiconductorlayer; and

a second electrode electrically connected to the second semiconductorlayer. In the Group III nitride semiconductor light-emitting device, aninsulating multilayer film intervenes between the second semiconductorlayer and the transparent electrode, wherein the insulating multilayerfilm has a first surface in contact with the second semiconductor layerand a second surface in contact with the transparent electrode. Theinsulating multilayer film serves as a distributed Bragg reflector andis formed in a region including a projection area obtained by projectingthe second electrode to the second semiconductor layer. The insulatingmultilayer film has a first region and a second region, wherein thefirst region has a layer thickness greater than 95% of the maximum filmthickness of the insulating multilayer film, and the second region has alayer thickness not greater than 95% of the maximum film thickness ofthe insulating multilayer film. The second surface of the insulatingmultilayer film in the second region has a slope having a dent portiondenting toward the first surface.

The Group III nitride semiconductor light-emitting device has aninsulating multilayer film. The insulating multilayer film serves as acurrent-blocking layer and also as a distributed Bragg reflector (DBR).Since the insulating multilayer film is provided with a dent portion,the insulating multilayer film has a reflection region and atransmission region. Therefore, the insulating multilayer film, servingas a current-blocking layer, inhibits current flow directly under thesecond electrode and realizes sufficient current diffusion in the lightemission face. Also, the insulating multilayer film reflects the lighttoward the second electrode, and suitably emits the other light to theoutside. Thus, a sufficiently wide insulating multilayer film can beformed, whereby the semiconductor light-emitting device exhibits highlight emission efficiency.

A second aspect of the technique is drawn to a specific mode of theGroup III nitride semiconductor light-emitting device, wherein, in across-section which is orthogonal to the first surface and whichincludes the first region and the second region, the thickness of theinsulating multilayer film, at a first point which is located on thesecond surface and which bisects the width of the second region, is 5%to 40% of the maximum film thickness of the insulating multilayer film.

A third aspect of the technique is drawn to a specific mode of the GroupIII nitride semiconductor light-emitting device, wherein, in across-section which is orthogonal to the first surface and whichincludes the first region and the second region, a second point at whichthe thickness of the insulating multilayer film is ½ the maximum filmthickness is located in closer vicinity to the first region, as comparedwith the first point which is located on the second surface and whichbisects the width of the second region.

A fourth aspect of the technique is drawn to a specific mode of theGroup III nitride semiconductor light-emitting device, wherein, in across-section which is orthogonal to the first surface and whichincludes the first region and the second region, the angle θ1 of a firstangle is larger than the angle θ2 of a second angle by ≧5°, wherein thefirst angle is formed between a first line connecting the first pointbisecting the width of the second region to a first end which is locatedon the second surface and which corresponds to 95% of the maximum filmthickness and the first surface of the insulating multilayer film, andthe second angle is formed between a second line connecting the firstpoint and a second end located at the periphery of the insulatingmultilayer film and the first surface of the insulating multilayer film.

A fifth aspect of the technique is drawn to a specific mode of the GroupIII nitride semiconductor light-emitting device, wherein the first angleθ1 is 15° to 45°.

A sixth aspect of the technique is drawn to a specific mode of the GroupIII nitride semiconductor light-emitting device, wherein the secondangle θ2 is 3° to 30°.

A seventh aspect of the technique is drawn to a specific mode of theGroup III nitride semiconductor light-emitting device, wherein the firstend which is located on the second surface and which corresponds to 95%of the maximum film thickness is located inside the projection area at adistance of 3 μm or less from the end of the production area, or outsidethe projection area at a distance of 7 μm or less from the end of theproduction area.

An eighth aspect of the technique is drawn to a specific mode of theGroup III nitride semiconductor light-emitting device, wherein, in aregion outside the first point which bisects the width of the secondregion, the insulating multilayer film satisfies the following equation:

d<λ/(4˜n)

(wherein d is a total thickness of insulating multilayer film, λ is awavelength of light, and n is a refractive index of one layer ofinsulating multilayer film).

In a ninth aspect of the present technique, there is provided a methodfor producing a Group III nitride semiconductor light-emitting device,the method comprising the following:

a first semiconductor layer formation step of forming a firstsemiconductor layer having a first conduction type;

a light-emitting layer formation step of forming a light-emitting layeron the first semiconductor layer;

a second semiconductor layer formation step of forming a secondsemiconductor layer having a second conduction type on thelight-emitting layer;

an insulating multilayer film formation step of forming an insulatingmultilayer film on a portion of the second semiconductor layer;

a transparent electrode formation step of forming a transparentelectrode on the insulating multilayer film and the remaining portion ofthe second semiconductor layer;

a first electrode formation step of forming a first electrode on thefirst semiconductor layer; and

a second electrode formation step of forming a second electrode on thetransparent electrode. The insulating multilayer film formation stepcomprises the following:

a resist application step of applying a resist;

a first exposure step of exposing to light a region other than aninsulating multilayer film formation region;

a baking step of heating the resist;

a second exposure step of exposing the entirety of the resist;

a hole-making step of removing a portion which has not been exposed tolight in the first exposure step, to thereby provide an end-widenedhole;

a film formation step of forming an insulating multilayer film insidethe hole; and

a resist removal step of removing the resist.

The present techniques provide a Group III nitride semiconductorlight-emitting device which realizes sufficient current diffusion in thelight emission face of the light-emitting layer and which attainssuitable light extraction to the outside, and a production methodtherefor.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features, and many of the attendant advantages ofthe present technique will be readily appreciated as the same becomesbetter understood with reference to the following detailed descriptionof the preferred embodiments when considered in connection with theaccompanying drawings, in which:

FIG. 1 is a schematic view of the configuration of a light-emittingdevice of an embodiment;

FIG. 2 is a view of the structure of an insulating multilayer film ofthe light-emitting device of the embodiment;

FIG. 3 is a view of the structure of an insulating multilayer film andother elements of the light-emitting device of the embodiment;

FIG. 4 is an enlarged view of the structure shown in FIG. 3;

FIG. 5 is a view showing the concepts of a reflection region and atransmission region in the light-emitting device of the embodiment;

FIG. 6 is a view (1) showing a step of forming an insulating multilayerfilm of the light-emitting device of the embodiment;

FIG. 7 is a view (2) showing a step of forming an insulating multilayerfilm of the light-emitting device of the embodiment;

FIG. 8 is a view (3) showing a step of forming an insulating multilayerfilm of the light-emitting device of the embodiment;

FIG. 9 is a view (4) showing a step of forming an insulating multilayerfilm of the light-emitting device of the embodiment;

FIG. 10 is a view (5) showing a step of forming an insulating multilayerfilm of the light-emitting device of the embodiment;

FIG. 11 is a view (6) showing a step of forming an insulating multilayerfilm of the light-emitting device of the embodiment;

FIG. 12 is a view (1) showing a method for forming the light-emittingdevice of the embodiment;

FIG. 13 is a view (2) showing a method for forming the light-emittingdevice of the embodiment;

FIG. 14 is a view (3) showing a method for forming the light-emittingdevice of the embodiment;

FIG. 15 is a view (4) showing a method for forming the light-emittingdevice of the embodiment;

FIG. 16 is a conceptual view (1) of a p-electrode formation region in anexperiment; and

FIG. 17 is a conceptual view (2) of a p-electrode formation region in anexperiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

With reference to the drawings, specific embodiment of the semiconductorlight-emitting device and the production method will next be describedin detail. However, this embodiment should not be construed as limitingthe technique thereto. The below-described stacking configuration of thelayers of the semiconductor light-emitting device and the electrodestructure are given only for the illustration purpose, and otherstacking structures differing therefrom may also be employed. Thethickness of each of the layers shown in the drawings is not an actualvalue, but a conceptual value.

First Embodiment 1. Semiconductor Light-Emitting Device

FIG. 1 is a schematic view of the configuration of a light-emittingdevice 100 of the first embodiment. The light-emitting device 100 is aface-up-type semiconductor light-emitting device. The light-emittingdevice 100 has a plurality of semiconductor layers formed of a Group IIInitride semiconductor. As shown in FIG. 1, the light-emitting device 100has a substrate 110, a buffer layer 120, an n-type contact layer 130, ann-side ESD layer 140, an n-side superlattice layer 150, a light-emittinglayer 160, a p-side superlattice layer 170, a p-type contact layer 180,an insulating multilayer film CB1, a transparent electrode TE1, ap-electrode P1, and an n-electrode N1.

On the main surface of the substrate 110, the buffer layer 120, then-type contact layer 130, the n-side ESD layer 140, the n-sidesuperlattice layer 150, the light-emitting layer 160, the p-sidesuperlattice layer 170, and the p-type contact layer 180 aresuccessively formed in this order. The n-electrode N1 is formed on then-type contact layer 130, and the p-electrode P1 is formed on thetransparent electrode TE1.

Each of the n-type contact layer 130, the n-side ESD layer 140, and then-side superlattice layer 150 is an n-type semiconductor layer. In thefirst embodiment, the n-type semiconductor layer is a firstsemiconductor layer of a first conduction type. Each of the p-sidesuperlattice layer 170 and the p-type contact layer 180 is a p-typesemiconductor layer. In the first embodiment, the p-type semiconductorlayer is a second semiconductor layer of a second conduction type.

In some cases, any of these layers may partially include a non-dopedlayer. Thus, the light-emitting device 100 includes an n-typesemiconductor layer, a light-emitting layer disposed on the n-typesemiconductor layer, the p-type semiconductor layer disposed on thelight-emitting layer, a transparent electrode TE1 disposed on the p-typesemiconductor layer, an n-electrode N1 electrically connected to then-type semiconductor layer, and a p-electrode P1 electrically connectedto the p-type semiconductor layer.

The substrate 110 is a growth substrate. On the main surface of thesubstrate 110, the aforementioned semiconductor layers are formedthrough MOCVD. The main surface of the substrate 110 is preferablyroughened. The substrate 110 is made of sapphire. Other than sapphire,materials such as SiC, ZnO, Si, GaN, and AlN may be employed.

The buffer layer 120 is formed on the main surface of the substrate 110.The buffer layer 120 is provided so as to form high-density crystalnuclei on the substrate 110. By virtue of the buffer layer 120, growthof a GaN layer having a flat surface is promoted. Examples of thematerial of the buffer layer 120 include AlN, GaN, BN, and TiN.

The n-type contact layer 130 is formed on the buffer layer 120. Then-type contact layer 130 is in contact with the n-electrode N1. That is,the n-type contact layer 130 is electrically connected to then-electrode N1. The n-type contact layer 130 is an n-type GaN layer. Then-type contact layer 130 may be composed of a plurality of layers havingdifferent carrier concentrations.

The n-side ESD layer 140 is an electrostatic breakdown-preventing layerfor preventing electrostatic breakdown of a semiconductor layer. Then-side ESD layer 140 is formed on the n-type contact layer 130. Then-side ESD layer 140 is formed by depositing an i-GaN layer formed ofnon-doped i-GaN and an n-type GaN layer formed of Si-doped n-type GaN.

The n-side superlattice layer 150 is a strain relaxation layer forrelaxing the stress applied to the light-emitting layer 160. The n-sidesuperlattice layer 150 has a superlattice structure. The n-sidesuperlattice layer 150 is, for example, a stacked body in which InGaNlayers and n-type GaN layers are repeatedly deposited.

The light-emitting layer 160 emits light through recombination of anelectron with a hole. The light-emitting layer 160 is formed on then-side superlattice layer 150. The light-emitting layer has at least awell layer and a barrier layer. The well layer may be, for example, anInGaN layer or a GaN layer. The barrier layer may be, for example, a GaNlayer or an AlGaN layer. These layers are examples, and other layerssuch as an AlInGaN layer may be employed.

The p-side superlattice layer 170 is formed on the light-emitting layer160. The p-side superlattice layer 170 is formed by repeatedlydepositing a stacked body composed of a p-type GaN layer, a p-type AlGaNlayer, and a p-type InGaN layer. The stacked structure is an example.Thus, the p-side superlattice layer 170 may have a stacking structurediffering from the above one.

The p-type contact layer 180 is formed on the p-side superlattice layer170. The p-type contact layer 180 is in contact with the transparentelectrode TE1. Thus, the p-type contact layer 180 is electricallyconnected to the p-electrode P1. The p-type contact layer 180 is formedof Mg-doped GaN.

The insulating multilayer film CB1 prevents current flow directly underthe p-electrode P1 and causes current to diffuse in the light emissionface. Also, the insulating multilayer film CB1 is a distributed Braggreflector (DBR). The insulating multilayer film CB1 is formed on a partof the p-type contact layer 180. The insulating multilayer film CB1intervenes between the transparent electrode TE1 and the part of thep-type contact layer 180.

The transparent electrode TE1 is formed on the insulating multilayerfilm CB1 and the remaining portion of the p-type contact layer 180. Thetransparent electrode TE1 is formed of ITO. Other than ITO, transparentoxides such as ICO, IZO, ZnO, TiO₂, NbTiO₂, and TaTiO₂ may be employed.

The p-electrode P1 is formed on the transparent electrode TE1. Thep-electrode P1 is in contact with the transparent electrode TE1. Thatis, the p-electrode P1 is electrically connected to the p-type contactlayer 180. The p-electrode P1 includes a V layer and an Al layersequentially formed from the surface of the transparent electrode TE1.Alternatively, this combination may be Ti and Al, or Ti and Au.

The n-electrode N1 is formed on the n-type contact layer 130. Then-electrode N1 is in contact with the n-type contact layer 130. That is,the n-electrode N1 is electrically connected to the n-type contact layer130. The n-electrode N1 includes a V layer and an Al layer sequentiallyformed from the surface of the n-type contact layer 130. Alternatively,this combination may be Ti and Al, or Ti and Au.

2. Insulating Multilayer Film 2-1. Structure of Insulating MultilayerFilm and Adjacent Layers

As shown in FIG. 1, the insulating multilayer film CB1 covers a part ofthe p-type contact layer 180. The transparent electrode TE1 covers theinsulating multilayer film CB1 and the remaining portion of the p-typecontact layer 180. The insulating multilayer film CB1 intervenes betweenthe p-type contact layer 180 and the transparent electrode TE1.

2-2. Structure of Insulating Multilayer Film

As described above, the insulating multilayer film CB1 is a distributedBragg reflector (DBR). Thus, as shown in FIG. 2, the insulatingmultilayer film CB1 is a stacking structure in which sets of two layershaving different refractive index are repeatedly stacked. Morespecifically, as shown in FIG. 2, the insulating multilayer film CB1 isformed through repeatedly and alternatingly forming first insulatinglayers CB1 a and second insulating layers CB1 b.

In the insulating multilayer film CB1, each of the first insulatinglayers CB1 a and the second insulating layers CB1 b is a transparentinsulator. The insulating multilayer film CB1 is formed throughrepeatedly forming, for example, SiO₂ layers and TiO₂ layers. Thematerial may also be Al₂O₃, or another material. The thickness of eachof the layers made of two kinds of materials may be predetermined inview of the refractive index of each material and the wavelength of theemitted light. Any number of repetition may be employed.

2-3. Position of Dent Portion

FIG. 3 is a cross-sectional view of the insulating multilayer film CB1and other elements in the vicinity of the film. The insulatingmultilayer film CB1 intervenes between the p-type contact layer 180 andthe transparent electrode TE1. The insulating multilayer film CB1 is incontact with the p-type contact layer 180 via the mediation of a firstsurface U1 of the film, and in contact with the transparent electrodeTE1 via a second surface U2 of the film. The first surface U1 is a flatplane, and the second surface U2 is a curved plane. As shown in FIG. 3,the insulating multilayer film CB1 is formed in a region including aprojection area PR1 obtained by projecting the p-electrode P1 to thep-type contact layer 180 (i.e., the first surface U1).

As shown in FIG. 3, the insulating multilayer film CB1 has a firstregion R1, and a second region R2 surrounding the first region R1. Thefirst region R1 has a layer thickness greater than 95% of the maximumfilm thickness of the insulating multilayer film CB1. Thus, the firstregion R1 is located at the central part of the insulating multilayerfilm CB1. The second region R2 has a layer thickness not greater than95% of the maximum film thickness of the insulating multilayer film CB1.Thus, the second region R2 is a peripheral region with respect to thefirst region R1. That is, the cross-section of FIG. 3 includes across-section orthogonal to the first surface U1, the cross-sectionincluding the first region R1 and the second region R2.

As shown in the cross-section of FIG. 3, the second surface U2 in thefirst region R1 of the insulating multilayer film CB1 is generally flat.The second surface U2 in the second region R2 of the insulatingmultilayer film CB1 has a slope L1. The slope L1 has a dent portion X1which dents toward the first surface U1 of the insulating multilayerfilm CB1. In the second region R2, the thickness of the insulatingmultilayer film CB1 steeply decreases, and the thickness reduction ratedecreases at a position corresponding to a certain thickness.

In FIG. 3, an imaginary line L2 is given. The line L2 imaginarilyconnects an end M1 to an end M2. The end M1 is a first end on the secondsurface U2 at which the thickness of CB1 is 95% of the maximum filmthickness. The end M1 is located at the boundary between the firstregion R1 and the second region R2. The end M2 is a second end on thesecond surface U2 which is located at the periphery of the insulatingmultilayer film CB1.

As shown in FIG. 3, the slope L1 has the dent portion X1. The dentportion X1 has a point K1. The point K1 is a point in the second surfaceU2 most distant from the line L2. The second region R2 includes an innerregion R2 a and an outer region R2 b. The inner region R2 a and theouter region R2 b have the same width in the cross-section. A point Q1and a point Q2 are located at the boundary between the inner region R2 aand the outer region R2 b. In other words, the points Q1 and Q2 arethose bisecting the width of the second region R2. The point Q1 islocated on the second surface U2, and the point Q2 is located on thefirst surface U1.

The point K1 is located in the inner region R2 a. That is, the point K1is located at a position in closer vicinity to the center, as comparedwith the point Q1, namely, is located in the vicinity of the firstregion R1. Thus, the point K1 is located in closer vicinity to the firstregion R1, as compared with the point Q1 bisecting the width of thesecond region R2.

2-4. Points Q1 and Q2 (on the Line Bisecting the Width of Second RegionR2)

Next will be described a cross-section orthogonal to the first surfaceU1, the cross-section including the first region R1 and the secondregion R2. The point Q1 is located on the second surface U2 and at theboundary between the inner region R2 a and the outer region R2 b. Thatis, the point Q1 is a first point which is located on the second surfaceU2 and which bisects the width of the second region R2. The thickness ofthe insulating multilayer film CB1 at the point Q1 is less than 50% ofthe maximum film thickness of the insulating multilayer film CB1. Thethickness is, for example, 5% to 40% of the maximum film thickness,preferably 10% to 30% of the maximum film thickness.

The point Q2 is located on the first surface U1 and at the boundarybetween the inner region R2 a and the outer region R2 b. That is, thepoint Q2 is located at the boundary between the insulating multilayerfilm CB1 and the p-type contact layer 180. The distance between thepoint Q1 and the point Q2 is equivalent to the film thickness of theinsulating multilayer film CB1 at the point Q1 bisecting the secondregion R2.

2-5. Point K2 (at the Position Corresponding to 50% Thickness)

The point K2 is a point at which the thickness of the insulatingmultilayer film CB1 is ½ the maximum film thickness. The point K2 islocated in the inner region R2 a. That is, the point K2 is a secondpoint which is located in closer vicinity to the first region R1, ascompared with the point Q1 bisecting the width of the second region R2.In other words, the point K2 is located in the more vicinity to thecenter, as compared with the point Q1; i.e., is in the vicinity of thefirst region R1, since the insulating multilayer film CB1 has the dentportion X1.

2-6. Angle of Slope

FIG. 4 is an enlarged view of a portion extracted from the insulatingmultilayer film CB1 shown in FIG. 3. In FIG. 4, a line J1 connecting theend M1 to the point Q1, and a line J2 connecting the end M2 and thepoint Q1 are given. The angle θ1 of a first angle is larger than theangle θ2 of a second angle by ≧5°. As shown in FIG. 4, the first angle(θ1) is formed between the line J1 and a surface U3 which is in parallelto the first surface U1 of the insulating multilayer film CB1. The firstangle (θ1) is equal to the angle between the line J1 and the firstsurface U1 of the insulating multilayer film CB1. The second angle (θ2)is an angle formed between the line J2 and the first surface U1 of theinsulating multilayer film CB1.

The angle (θ1) is 15° to 45°, preferably 20° to 35°. The angle (θ2) is3° to 30°, preferably 5° to 20°. The angle ranges are merely examples,and other angle values may be acceptable.

3. Effects of Insulating Multilayer Film 3-1. Reflection Region andLight Transmission Region (Hereinafter Referred to Simply asTransmission Region)

As shown in FIG. 5, the light-emitting device 100 of the firstembodiment has a reflection region RR1 and a transmission region RT1.The reflection region RR1 includes the first region R1 and a portion ofthe second region R2. The transmission region RT1 includes the remainingportion of the second region R2.

The thickness of the reflection region RR1 is sufficiently greater thanthe wavelength of the light emitted by the light-emitting layer 160. Theinsulating multilayer film CB1 is formed so as to reflect the lightemitted by the light-emitting layer 160. Thus, in the reflection regionRR1, light LG3 emitted by the light-emitting layer 160 toward thep-electrode P1 is reflected by the insulating multilayer film CB1 towardthe semiconductor layer. As shown in FIG. 5, light LG3 is reflected bythe first surface U1, which is a surface of the insulating multilayerfilm CB1. However, the light emitted by the light-emitting layer 160toward the p-electrode P1 may be reflected by a plane in the insulatingmultilayer film CB1 at a deeper level.

The film thickness of the transmission region RT1 is sufficiently small,as compared with the wavelength of the light emitted by thelight-emitting layer 160. Thus, the thickness does not meet thefollowing equation:

n·d=λ/4

(wherein n is a refractive index, d is a film thickness, and λ is awavelength of light). Thus, the transmission region RT1 cannot reflectthe light but transmits it. In other words, in the transmission regionRT1, the light (LG1 and LG2) emitted by the light-emitting layer 160 istransmitted to the outside. Thus, light is extracted.

The outer region Rb2 is included in the transmission region RT1. Thus,in the outer region R2 b, the insulating multilayer film CB1 satisfiesthe following equation:

d<λ/(4·n)

(wherein d is a total thickness of insulating multilayer film, λ is awavelength of light, and n is a refractive index of one layer ofinsulating multilayer film).

The boundary between the reflection region RR1 and the transmissionregion RT1 is determined by wavelength of light (λ) and film thickness(d). In addition, as shown in FIG. 5, when the light is emitted towardthe same position, the film thickness of CB1 varies depending on thelight incident angle. Thus, light LG4 transmits through the insulatingmultilayer film CB1, but light LG5 is reflected by the insulatingmultilayer film CB1. In this way, the boundary between the reflectionregion RR1 and the transmission region RT1 is not always definite. Thus,in the vicinity of this boundary, light transmits or does not transmit,depending on the incident angle.

Therefore, the reflection region RR1 and the transmission region RT1 arenot actual regions but conceptual regions. However, as shown in FIG. 5,the light (LG5) emitted toward the p-electrode P1 can be reflected, andthe light (LG4) emitted not toward the p-electrode P1 can be suitablyextracted.

3-2. Role as Current-Blocking Layer

The insulating multilayer film CB1 also serves as a current-blockinglayer. Thus, the insulating multilayer film CB1 can be designed to havea large size. The insulating multilayer film CB1, serving as acurrent-blocking layer, realizes sufficient current diffusion and canemit light at high efficiency to the outside, at the peripheral portionof the device. Furthermore, the insulating multilayer film CB1suppresses light absorption by the p-electrode P1. Accordingly, thelight-emitting device 100 exhibits excellent light emission efficiency.

3-3. Other Effects

The percent change in the angle of the slope L1 is not very large. Thus,breakage of the transparent electrode TE1 on the second surface U2 isvirtually prevented.

4. Method of Forming an Insulating Multilayer Film

The insulating multilayer film CB1 of the first embodiment has a uniquestructure as shown in FIGS. 3 and 4 and other drawings. The insulatingmultilayer film CB1 is formed through the following procedure.

4-1. Resist Application Step

Firstly, as shown in FIG. 6, a resist RS1 is applied onto the p-typecontact layer 180. The resist RS1 can be dissolved in a specific solventthrough exposure to light and becomes insoluble and stable through heattreatment. Examples of the resist RS1 include AZ5214 (product ofClariant (Japan) K.K.).

4-2. First Light Exposure Step

Next, as shown in FIG. 7, the resist RS1 is exposed to light through amask MS1. The mask MS1 has almost the same area as the area where theinsulating multilayer film CB1 is to be formed. Thus, in the firstexposure step, an area excepting the insulating multilayer film CB1formation region is mainly exposed to light. Through first lightexposure, the portion RS1 a of the resist RS1, which has been exposed tolight, can be dissolved in a specific solvent. In contrast, the area RS1b of the resist RS1, which has not been exposed to light, is stillinsoluble to the same solvent. The area which is not covered with themask MS1 is irradiated with light to the full depth of the resist RS1.In contrast, the area which is covered with the mask MS1 is neverirradiated with light to the full depth of the resist RS1. At theinterface between the two areas of the resist RS1, a portion of theresist RS1 to a certain depth is irradiated with light, and theremaining portion thereof is not irradiated with light.

4-3. Baking Step

Then, as shown in FIG. 8, the resist RS1 is heated to a predeterminedtemperature. The baking temperature varies depending on the type of theresist RS1. The portion RS1 a is converted to a portion RS1 c throughfirst light exposure. The portion RS1 c is insoluble and stable in thepredetermined solvent. In contrast, the portion RS1 b, which has notundergone first light exposure, remains insoluble in the same solvent.

4-4. Second Light Exposure Step

Then, as shown in FIG. 9, the entirety of the resist RS1 is exposed tolight (i.e., second light exposure). The second light exposure iscarried out without use of a mask. The portion RS1 d is a region whichhas not undergone first light exposure but has undergone second lightexposure. Through second light exposure, the portion RS1 d comes to havesolubility in a specific solvent. The portion RS1 c is a region whichhas undergone first light exposure and second light exposure. Theportion RS1 c is insoluble and stable after the baking step. Thus, theportion RS1 c remains insoluble and stable in the solvent.

4-5. Hole-Making Step

Next, the soluble portion RS1 d of the resist RS1 is dissolved in aspecific solvent. That is, the portion which has not been exposed tolight in the first light exposure step is removed. Through thisprocedure, a hole Y1 for forming the insulating multilayer film CB1 isprovided, as shown in FIG. 10. The shape of the hole Y1 is almost thesame as that of the insulating multilayer film CB1. The hole Y1 has anend-widened shape. That is, the diameter of the hole Y1 increases fromthe opening thereof to the bottom.

4-6. Film Formation Step

Then, as shown in FIG. 11, the insulating multilayer film CB1 is formedinside the hole Y1, which is a void portion of the resist RS1. The filmmay be formed through electron beam vapor deposition. Alternatively,electron beam vapor deposition and an ion gun technique may be employedin combination. Yet alternatively, sputtering may be employed. In thefilm formation step, the insulating multilayer film CB1 is formed suchthat the void of the hole Y1 is substantially buried. However, a certainamount of remaining space may be acceptable. Even in such a case, theinsulating multilayer film CB1 having the aforementioned shape can beformed.

4-7. Resist Removal Step

Subsequently, the resist RS1 is removed. Specifically, the portion RS1 cis removed by use of a chemical liquid which can remove the resist RS1.Through the aforementioned procedure, the insulating multilayer film CB1can be formed on the p-type contact layer 180.

5. Method for Producing Semiconductor Light-Emitting Device

Next will be described a method for producing the light-emitting device100 of the first embodiment. In the first embodiment, the semiconductorcrystal layers are formed through epitaxial growth based on metalorganicchemical vapor deposition (MOCVD). Accordingly, the production methodincludes the following: a first semiconductor layer formation step offorming a first semiconductor layer having a first conduction type; alight-emitting layer formation step of forming a light-emitting layer onthe first semiconductor layer; a second semiconductor layer formationstep of forming a second semiconductor layer having a second conductiontype on the light-emitting layer; an insulating multilayer filmformation step of forming an insulating multilayer film on a portion ofthe second semiconductor layer; a transparent electrode formation stepof forming a transparent electrode on the insulating multilayer film andthe remaining portion of the second semiconductor layer; a firstelectrode formation step of forming a first electrode on the firstsemiconductor layer; and a second electrode formation step of forming asecond electrode on the transparent electrode.

Examples of the carrier gas employed in the growth of semiconductorlayers include hydrogen (H₂), nitrogen (N₂), and a mixture of hydrogenand nitrogen (H₂+N₂). Ammonia gas (NH₃) is used as a nitrogen source,and trimethylgallium (Ga(CH₃)₃: (TMG)) is used as a gallium source.Trimethylindium (In(CH₃)₃: (TMI) is used as an indium source, andtrimethylaluminum (Al(CH₃)₃: (TMA) is used as an aluminum source. Silane(SiH₄) is used as an n-type dopant gas, and cyclopentadienylmagnesium(Mg(C₅H₅)₂) is used as a p-type dopant gas.

5-1. n-Type Contact Layer Formation Step

Firstly, the substrate 110 is cleaned with hydrogen gas. Then, thebuffer layer 120 is formed on the main surface of the substrate 110, andthe n-type contact layer 130 is formed on the buffer layer 120. Duringthe above layer formation, the substrate temperature is 1,080° C. to1,140° C.

5-2. n-Side ESD Layer Formation Step

Subsequently, the n-side ESD layer 140 is formed on the n-type contactlayer 130. For forming the i-GaN layer, feed of silane (SiH₄) isstopped. In this procedure, the substrate temperature is, for example,750° C. to 950° C. Then, for forming n-type GaN, feed of silane (SiH₄)is started again. In the subsequent procedure, the substrate temperatureis 750° C. to 950° C., which is the same range as employed in theformation of the i-GaN layer.

5-3. n-Side Superlattice Layer Formation Step

Then, the n-side superlattice layer 150 is formed on the n-side ESDlayer 140. In one specific mode, InGaN layers and n-type GaN layers arerepeatedly deposited. In this procedure, the substrate temperature is,for example, 700° C. to 950° C.

5-4. Light-Emitting Layer Formation Step

On the n-side superlattice layer 150, the light-emitting layer 160 isformed. In one specific mode, InGaN layers, GaN layers, and AlGaN layersare repeatedly deposited. In this procedure, the substrate temperatureis, for example, 700° C. to 900° C.

5-5. p-Side Superlattice Layer Formation Step

On the light-emitting layer 160, the p-side superlattice layer 170 isformed. In one specific mode, p-type GaN layers, p-type AlGaN layers,and p-type InGaN layers are repeatedly deposited.Cyclopentadienylmagnesium (Mg(C₅H₅)₂) may be used as a p-type dopantgas.

5-6. p-Type Contact Layer Formation Step

On the p-side superlattice layer 170, the p-type contact layer 180 isformed. The substrate temperature is adjusted to fall within a range of900° C. to 1,100° C. Through this procedure, these semiconductor layersare formed on the substrate 110, as shown in FIG. 12.

5-7. Insulating Multilayer Film Formation Step

Subsequently, as shown in FIG. 13, the insulating multilayer film CB1 isformed on a portion of the p-type contact layer 180. For this purpose,as described above, the resist application step, the first exposurestep, the baking step, the second exposure step, the hole-making step,the film formation step, and the resist removal step are performed.

5-8. Transparent Electrode Formation Step

Then, as shown in FIG. 14, the transparent electrode TE1 is formed onthe insulating multilayer film CB1 and the remaining portion of thep-type contact layer 180. The transparent electrode TE1 may be formedthrough sputtering or a vapor deposition technique. Through thisprocedure, the insulating multilayer film CB1 is covered with the p-typecontact layer 180 and the transparent electrode TE1. On a portion of thep-type contact layer 180, where a dent portion for exposing the n-typecontact layer 130 is to be provided, the transparent electrode TE1 isnot necessarily formed.

5-9. Electrode Formation Step

On the transparent electrode TE1, the p-electrode P1 is formed. As shownin FIG. 15, the semiconductor layers are partially removed through laserradiation or etching from the p-type contact layer 180 side, to therebyexpose the n-type contact layer 130. Then, the n-electrode N1 is formedon the thus-exposed region. Either of the p-electrode P1 formation stepand the n-electrode N1 formation step may be performed first.

5-10. Other Steps

In addition to the aforementioned steps, additional steps such as a stepof covering the device with a protective film and a heat treatment stepmay be carried out. Notably, the step of exposing the n-type contactlayer 130 may be performed at any timing, so long as the p-type contactlayer 180 has already been formed. In this way, the light-emittingdevice 100 shown in FIG. 1 is produced.

6. Experiments 6-1. Preparation of Samples

Next will be described in detail experiments performed so as to checkperformance of the insulating multilayer film CB1 of the firstembodiment. Samples of the insulating multilayer film CB1 were preparedin the following manner. In the experiments, SiO₂ (75 nm) and TiO₂ (49nm) were alternatingly stacked, and the stacking operation wasrepeatedly performed 8 times, to thereby form an insulating multilayerfilm CB1. Samples for Examples 1 to 4 each were provided with thethus-formed insulating multilayer film CB1.

In the experiments of Examples 1 to 4, as shown in FIGS. 16 and 17, thewidth of the p-electrode P1 was varied. There were prepared a sample inwhich the width of the p-electrode P1 was adjusted to be smaller thanthe distance between ends M1 as shown in FIG. 16, and a sample in whichthe width of the p-electrode P1 was adjusted to be greater than thedistance between ends M1 as shown in FIG. 17. As Comparative Example 1,an SiO₂ layer (film thickness: 130 nm) was formed. The SiO₂ layer was asingle-layer film, and the shape of the SiO₂ film differed from that ofthe insulating multilayer film CB1 of the first embodiment.

6-2. Experimental Results

Table 1 shows the results of the experiments. Regarding the locationalfeatures shown in Table 1, the case in which the end P1 a of thep-electrode P1 was in closer vicinity to the center as compared with theend M1 as shown in FIG. 16 is denoted by “+,” whereas the case in whichthe end M1 was in closer vicinity to the center as compared with the endP1 a of the p-electrode P1 as shown in FIG. 17 is denoted by “−.” InExample 1, the width d1 in FIG. 16 was +2 μm. In Example 2, the width d1in FIG. 16 was +4 μm. In Example 3, the width d1 in FIG. 16 was +6 μm.In Example 4, the width d2 in FIG. 17 was −2 μm.

Also, in Table 1, the case in which a target light-emitting device hadno insulating multilayer film CB1 or SiO₂ single-layer film was employedas a standard of percent rise in total radiant flux. That is, when thetarget light-emitting device had no insulating multilayer film CB1 orSiO₂ single-layer film, the percent rise in total radiant flux was 0%.

As shown Table 1, the percent rise in total radiant flux of the sampleof Example 1 was 1.15%; the percent rise in total radiant flux of thesample of Example 2 was 0.92%; the percent rise in total radiant flux ofthe sample of Example 3 was 0.83%; and the percent rise in total radiantflux of the sample of Example 4 was 0.85%. Thus, in Examples 1 to 4, thepercent rise in total radiant flux was higher than 0.8%.

The percent rise in total radiant flux of the sample of ComparativeExample 1 was 0.68%, which is lower than 0.7%. Accordingly, the percentrise in total radiant flux is higher in Examples 1 to 4 than inComparative Example 1.

Thus, in the case where the end M1 of the insulating multilayer film CB1is in the more vicinity (by ≦3 μm) of the center as compared with theend P1 a of the p-electrode P1, or in the case where the end M1 of theinsulating multilayer film CB1 is further away (by ≦7 μm) from thecenter as compared with the end P1 a of the p-electrode P1 (i.e., theend of the projection region PR1), the total radiant flux of thelight-emitting device 100 is great.

Preferably, in the case where the end M1 of the insulating multilayerfilm CB1 is further away (by 0 to 5 μm) from the center as compared withthe end P1 a of the p-electrode P1, the total radiant flux of thelight-emitting device 100 is greater. More preferably, in the case wherethe end M1 of the insulating multilayer film CB1 is further away (by 1to 4 μm) from the center as compared with the end P1 a of thep-electrode P1, the total radiant flux of the light-emitting device 100is further greater.

TABLE 1 Locational % Rise in total Insulating layer feature radiant fluxEx. 1 Insulating multilayer film +2 μm 1.15% Ex. 2 Insulating multilayerfilm +4 μm 0.92% Ex. 3 Insulating multilayer film +6 μm 0.83% Ex. 4Insulating multilayer film −2 μm 0.85% Comp. Ex. 1 SiO₂ single-layerfilm +3 μm 0.68%

7. Variants 7-1. Type of Light-Emitting Device

The light-emitting device 100 of the first embodiment is a face-up-typelight-emitting device, having one contact electrode (transparentelectrode TE1). However, alternatively, the light-emitting device of thepresent technique may be a flip-chip-type light-emitting device, havinga plurality of contact electrodes.

7-2. Conduction Type

In the first embodiment, the first conduction type was n-type, and thesecond conduction type was p-type. However, the combination ofconduction type may be inverted. That is, the first conduction type maybe p-type, and the second conduction type may be n-type.

7-3. Number of Dent Portion(s)

The slope L1 of the light-emitting device 100 of the first embodimenthas one dent portion X1. However, alternatively, the slope L1 may havetwo or more dent portions observed in a cross-section.

8. Summary of First Embodiment

As described hereinabove, the light-emitting device 100 of the firstembodiment has a first region R1 and a second region R2 surrounding thefirst region R1. The first region R1 has a layer thickness greater than95% of the maximum film thickness of the insulating multilayer film CB1and is located at the central part of the insulating multilayer filmCB1. The second region R2 has a layer thickness not greater than 95% ofthe maximum film thickness of the insulating multilayer film CB1 and isa peripheral region with respect to the first region R1. In across-section of the light-emitting device, the second region R2includes a dent portion X1. By virtue of such a structure, theinsulating multilayer film CB1 has a reflection region RR1, whichreflects light, and a transmission region RT1, which transmits light.Thus, according to the light-emitting device 100, the light emittedtoward the p-electrode P1 can be reflected, and the light emitted nottoward the p-electrode P1 can be suitably extracted.

The method for producing the semiconductor light-emitting device of thefirst embodiment includes a resist application step, a first exposurestep, a baking step, a second exposure step, a hole-making step, a filmformation step, and a resist removal step. According to the productionmethod, the first region R1 having a large film thickness, and thesecond region R2 having a small film thickness can be suitably formed.

The aforementioned embodiments are merely examples. It is thereforeunderstood that those skilled in the art can provide variousmodifications and variations of the technique, so long as those fallwithin the scope of the present technique. The stacking structure of thestacked body should not be limited to those as illustrated, and thestacking structure, the number of repetition of component layers, andother factors may be arbitrarily chosen. The semiconductor layer growthtechnique is not limited to metalorganic chemical vapor deposition(MOCVD), and other techniques such as hydride vapor phase epitaxy (HVPE)and other liquid-phase epitaxy techniques may also be employed.

What is claimed is:
 1. A Group III nitride semiconductor light-emittingdevice comprising: a first semiconductor layer having a first conductiontype; a light-emitting layer disposed on the first semiconductor layer;a second semiconductor layer having a second conduction type, the layerbeing disposed on the light-emitting layer; a transparent electrodedisposed on the second semiconductor layer; a first electrodeelectrically connected to the first semiconductor layer; and a secondelectrode electrically connected to the second semiconductor layer;wherein the Group III nitride semiconductor light-emitting devicecomprises an insulating multilayer film which intervenes between thesecond semiconductor layer and the transparent electrode, the insulatingmultilayer film comprising a first surface in contact with the secondsemiconductor layer and a second surface in contact with the transparentelectrode; the insulating multilayer film serves as a distributed Braggreflector and is formed in a region including a projection area obtainedby projecting the second electrode to the second semiconductor layer;the insulating multilayer film comprises a first region and a secondregion, wherein the first region comprises a layer thickness greaterthan 95% of the maximum film thickness of the insulating multilayerfilm, and the second region comprises a layer thickness not greater than95% of the maximum film thickness of the insulating multilayer film; andthe second surface of the insulating multilayer film in the secondregion comprises a slope having a dent portion denting toward the firstsurface.
 2. The Group III nitride semiconductor light-emitting deviceaccording to claim 1, wherein, in a cross-section which is orthogonal tothe first surface and which includes the first region and the secondregion, the thickness of the insulating multilayer film, at a firstpoint which is located on the second surface and which bisects the widthof the second region, is 5% to 40% of the maximum film thickness of theinsulating multilayer film.
 3. The Group III nitride semiconductorlight-emitting device according to claim 1, wherein, in a cross-sectionwhich is orthogonal to the first surface and which includes the firstregion and the second region, a second point at which the thickness ofthe insulating multilayer film is ½ the maximum film thickness islocated in closer vicinity to the first region, as compared with thefirst point which is located on the second surface and which bisects thewidth of the second region.
 4. The Group III nitride semiconductorlight-emitting device according to claim 2, wherein, in a cross-sectionwhich is orthogonal to the first surface and which includes the firstregion and the second region, a second point at which the thickness ofthe insulating multilayer film is ½ the maximum film thickness islocated in closer vicinity to the first region, as compared with thefirst point which is located on the second surface and which bisects thewidth of the second region.
 5. The Group III nitride semiconductorlight-emitting device according to claim 1, wherein, in a cross-sectionwhich is orthogonal to the first surface and which includes the firstregion and the second region, the angle θ1 of a first angle is largerthan the angle θ2 of a second angle by ≧5°, wherein the first angle isformed between a first line connecting the first point bisecting thewidth of the second region to a first end which is located on the secondsurface and which corresponds to 95% of the maximum film thickness andthe first surface of the insulating multilayer film, and the secondangle is formed between a second line connecting the first point and asecond end located at the periphery of the insulating multilayer filmand the first surface of the insulating multilayer film.
 6. The GroupIII nitride semiconductor light-emitting device according to claim 2,wherein, in a cross-section which is orthogonal to the first surface andwhich includes the first region and the second region, the angle θ1 of afirst angle is larger than the angle θ2 of a second angle by ≧5°,wherein the first angle is formed between a first line connecting thefirst point bisecting the width of the second region to a first endwhich is located on the second surface and which corresponds to 95% ofthe maximum film thickness and the first surface of the insulatingmultilayer film, and the second angle is formed between a second lineconnecting the first point and a second end located at the periphery ofthe insulating multilayer film and the first surface of the insulatingmultilayer film.
 7. The Group III nitride semiconductor light-emittingdevice according to claim 3, wherein, in a cross-section which isorthogonal to the first surface and which includes the first region andthe second region, the angle θ1 of a first angle is larger than theangle θ2 of a second angle by ≧5°, wherein the first angle is formedbetween a first line connecting the first point bisecting the width ofthe second region to a first end which is located on the second surfaceand which corresponds to 95% of the maximum film thickness and the firstsurface of the insulating multilayer film, and the second angle isformed between a second line connecting the first point and a second endlocated at the periphery of the insulating multilayer film and the firstsurface of the insulating multilayer film.
 8. The Group III nitridesemiconductor light-emitting device according to claim 4, wherein, in across-section which is orthogonal to the first surface and whichincludes the first region and the second region, the angle θ1 of a firstangle is larger than the angle θ2 of a second angle by ≧5°, wherein thefirst angle is formed between a first line connecting the first pointbisecting the width of the second region to a first end which is locatedon the second surface and which corresponds to 95% of the maximum filmthickness and the first surface of the insulating multilayer film, andthe second angle is formed between a second line connecting the firstpoint and a second end located at the periphery of the insulatingmultilayer film and the first surface of the insulating multilayer film.9. The Group III nitride semiconductor light-emitting device accordingto claim 5, wherein the first angle θ1 is 15° to 45°.
 10. The Group IIInitride semiconductor light-emitting device according to claim 6,wherein the first angle θ1 is 15° to 45°.
 11. The Group III nitridesemiconductor light-emitting device according to claim 5, wherein thesecond angle θ2 is 3° to 30°.
 12. The Group III nitride semiconductorlight-emitting device according to claim 6, wherein the second angle θ2is 3° to 30°.
 13. The Group III nitride semiconductor light-emittingdevice according to claim 9, wherein the second angle θ2 is 3° to 30°.14. The Group III nitride semiconductor light-emitting device accordingto claim 10, wherein the second angle θ2 is 3° to 30°.
 15. The Group IIInitride semiconductor light-emitting device according to claim 1,wherein the first end which is located on the second surface and whichcorresponds to 95% of the maximum film thickness is located inside theprojection area at a distance of 3 μm or less from the end of theproduction area, or outside the projection area at a distance of 7 μm orless from the end of the production area.
 16. The Group III nitridesemiconductor light-emitting device according to claim 2, wherein thefirst end which is located on the second surface and which correspondsto 95% of the maximum film thickness is located inside the projectionarea at a distance of 3 μm or less from the end of the production area,or outside the projection area at a distance of 7 μm or less from theend of the production area.
 17. The Group III nitride semiconductorlight-emitting device according to claim 1, wherein, in a region outsidethe first point which bisects the width of the second region, theinsulating multilayer film satisfies the following equation:d<λ/(4·n) (wherein d is a total thickness of insulating multilayer film,λ is a wavelength of light, and n is a refractive index of one layer ofinsulating multilayer film).
 18. The Group III nitride semiconductorlight-emitting device according to claim 2, wherein, in a region outsidethe first point which bisects the width of the second region, theinsulating multilayer film satisfies the following equation:d<λ/(4·n) (wherein d is a total thickness of insulating multilayer film,λ is a wavelength of light, and n is a refractive index of one layer ofinsulating multilayer film).
 19. A method for producing a Group IIInitride semiconductor light-emitting device, the method comprising:forming a first semiconductor layer having a first conduction type;forming a light-emitting layer on the first semiconductor layer; forminga second semiconductor layer having a second conduction type on thelight-emitting layer; forming an insulating multilayer film on a portionof the second semiconductor layer; forming a transparent electrode onthe insulating multilayer film and the remaining portion of the secondsemiconductor layer; forming a first electrode on the firstsemiconductor layer; and forming a second electrode on the transparentelectrode, wherein the insulating multilayer film formation stepcomprises the following: applying a resist; exposing to light a regionother than an insulating multilayer film formation region; heating theresist; exposing the entirety of the resist; removing a portion whichhas not been exposed to light in the first exposure step, to therebyprovide an end-widened hole; forming an insulating multilayer filminside the hole; and removing the resist.